Stabilized hydrocarbon fuel oils



Patented Mar. 24, 1953 UNITED STATES PATENT OFFICE Audubon, N. J., assignors to Gulf Oil Corporation, Pittsburgh, Pa, a corporation of Pennsylvam'a No Drawing. Application August 28, 1950, Serial No. 181,938

4 Claims.

This invention relates to stabilized hydrocarbon fuel oils, and more particularly to furnace oils, diesel fuels, and the like, stabilized against discoloration, the formation of sludge, and undesirable degradation products appearing after storage of the fuel. The invention is primarily concerned with fuels commonly referred to as middle oil distillates, as will more fully appear hereinafter.

The storage of fuel oils, furnace oils, and the like is in many instances complicated by the formation of undesirable products in the fuel oils as evidenced in several ways. After prolonged periods of storage many fuels tend to discolor, and ultimately insoluble material is formed in the fuel. This insoluble material prelcipitates out and leads to the formation of sludge. These products, and possibly others remaining in the fuel oils, cause the clogging of screens, conduits and other parts of burners, the formation of deposits on burners, commonly referred to as toadstools, and exhibit additional undesirable properties.

The degradation of fuel oils upon storage is apparently due to the action of air in contact with the fuel, coupled with the effect of light, particularly ultraviolet radiation. This degradation is generally believed to be the result of three types of reactions. Two of these, oxidation and polymerization of unsaturates, probably account for a great deal of the contaminants appearing after prolonged periods of storage. In addition, where cracked distillates resulting from catalytic cracking operations are blended with fuel oils, the discoloration of the fuel and formation of sludge appears to be aggravated. This is probably due to the rearrangement or activation of sulfur compounds contained in the cracked distillates. In this active state such compounds may catalyze the oxidation and polymerization of unsaturated compounds and/or the sulfur compounds may react with the olefinic hydrocarbons to form soluble polymers which discolor the fuel. In all probability, all of these reactions take place upon storage, so that fuels which have been stored for many months may be characterized by discoloration, the formation of insoluble material, acidity and other deleterious properties.

The discoloration of fuels is particularly aggravated in the case of fuels which have been exposed to light while'under storage conditions. This difficulty is encountered with both cracked and uncracked fuels, although the problem appears to be serious in the case of uncracked fuels only when high sulfur stocks are involved or the sulfur is in a particularly active state.

An acceptable fuel for use in oil burners and diesel engines must, of course, be free from any tendency to clog filter screens and the numerous fine passages and openings present in fuel oil burners and in diesel engines. The fuel oil used in such equipment can interfere with the performance of various parts in several ways, among which are clogging, summing, and corrosion. Particularly detrimental to good performance are sediments, which may be of the so-called casual or non-casual types. Casual sediments include sand, dirt, iron rust, dust, water, emulsions and miscellaneous debris. Casual sediments may be avoided by simply keeping the original oil clean and free from extraneous insoluble materials. The non-casual sediment is that sediment which may form in an oil during use or storage. Such sediment is an organic material originating mainly in oxidation and polymerization of all, or a portion of, the oil. As has been stated, this oxidation and polymerization results from the presence of oxygen or air and probably also is due to the presence of certain active sulfur compounds. The non-casual sediments may be very finely divided so as to form a sediment clogging small openings and fine pores of filters; in some cases they further coagulate in the form of coarser sediment forming massive deposits which clog filters and other parts of equipment.

The clogging of copper or copper bearing screens and filters in burners and other equipment is encountered to some extent with uncracked fuels, particularly if petroleum acids are not neutralized or washed out, therefore steps of neutralization and washing should be taken for any distillates containing materials of high neutralization number. In addition, trouble may also be encountered with furnace oils containing cracked distillates through the action of so-called oxyacids which are frequently developed in cracked fuels. There appears to be a tendency for such acids to form reaction products with the copper and copper bearing screens and filters. These products tend to coat the wires so as to clog or reduce the size of the open mesh of openings such that even fine insoluble matter will clog them.

The tendency of fuels to clog filters varies with different fuels. However, certain fuels comprising a mixture of uncracked and cracked distillates have a greater tendency to form the noncasual sediment than do the cracked fuels alone. This is probably due to the fact that the decomposition products are less soluble in the uncracked distillates and therefore tend to precipitate out. As pointed out, although the development and settling out of insoluble matter is particularly prevalent with mixtures of cracked and uncracked distillates, this action appears to be more pronounced for high sulfur distillates, either cracked or uncracked.

Acute trouble due to these problems is not likely to be developed with screens and filters in a system where fresh stocks that have not been in storage for a long time are employed. However, diificulties are likely to be encountered by users of furnace oils who have allowed furnaces to remain inactive and the oil to remain in storage over the summer months. In such cases the development and settling out of some insoluble matter may thus be concentrated in the first pumpings when the furnace is started up in the fall.

It has been noted that certain fuels do not begin to clog filters until such fuels have been passed through the filter for a period of time. The period in which there is no substantial clo ging of the filter is referred to as the induction period. Obviously, it is highly desirable for a fuel to have a longer induction period since this increases the life of the filter and eliminates frequent shut-downs and operational failures.

It is therefore an object of this invention to provide hydrocarbon fuel oils having improved stability on storage.

More particularly, it is an object of this invention to provide hydrocarbon fuel oils of improved stability against the formation of undesirable color bodies as well as the development and settling out of insoluble matter on storage.

Another object of this invention is to provide improved hydrocarbon fuels having substantially non-clogging tendencies to screens and filters and having a relatively long induction period.

These and other objects are accomplished by the present invention wherein we provide improved fuels, stabilized against the formation of undesirable color bodies and against sludge, comprising a major amount of a hydrocarbon fuel oil and a minor amount, sufficient to inhibit the formation of insoluble matter and undesirable color bodies, of (l) a metallo compound obtained by reacting'an aqueous slurry of a metal hydroxide selected from the group consisting of barium, strontium, magnesium and calcium hydroxides with formaldehyde at a mildly elevated temperature and condensing the resulting product with aniline and a mono-alkyl phenol having 4 to 12 carbon atoms in the alkyl substituent, and (2) a condensation product obtained by reacting, at a mildly elevated temperature, formaldehyde and ammonium hydroxide with a mono-alkyl phenol having from 4 to 12 carbon atoms in the alkyl substituent.

(1) The metallo compound, which is added to fuel oils 'in accordance with the present invention, is described and claimed in the copending application of Smith, Cantrell, and Peters, Serial No. 790,440, filed December 8, 1947, now U. S. Patent No. 2,5i5,113. This compound is also disclosed and claimed in fuel oil compositions in the copending application of Smith, Cantrell, and Peters, Serial No. 181,936, filed August 28, 1950.

As shown therein, the metallo compound is prepared by first reacting an aqueous slurry of the metal hydroxide and formaldehyde at a mildly elevated temperature, say 160 F., but not exceeding 200 F. The exact nature of this reaction product is unknown, but the reaction product contains combined therein the metal of the metal hydroxide. This product is then condensed with aniline and a mono-alkyl phenol having from 4 to 12 carbon atoms in the alkyl substituent. The condensation between the reaction product of the metal hydroxide and formaldehyde, and the aniline and phenol proceeds spontaneously upon mixing the reactants. Since the reaction is exothermic, care should be taken not to allow the temperature to exceed about 200 F., otherwise dark colored, highly resinous, insoluble products may result. After the condensation is completed, the temperature is raised to distill off all water, both that formed in the condensation and added with the reactants. The reactants are preferably employed in the proportions of 1 mol of metal hydroxide, 2 to 4 mols of formaldehyde, 0.5 to 1.0 mol of aniline and 2 to 4 mols of the mono-alkyl phenol.

(2) The ammonia condensation products are disclosed and claimed in fuel oil compositions in the copending application of Smith and Cantrell, Serial No. 181,935, filed August 28, 1950. As shown therein the products are preferably prepared by the simultaneous reaction of ammonium hydroxide, formaldehyde and the alkyl phenol, at a mildly elevated temperature, say but not exceeding 200 F., since the reaction is exothermic and undesirable products are apt to result if the temperature is allowed to become too high. After the condensation is completed the temperature is raised to distill off all water, both that formed in the condensation and that added with the reactants. The reactants are preferably employed in the proportions of 1 mol of ammonium hydroxide, 1 to 5 mols of formaldehyde and l to 4 mols of mono-alkyl phenol.

Although it is preferred to employ the reactants simultaneously, or to first react the alkyl phenol and ammonium hydroxide, followed by condensation with formaldehyde, we have found that the reaction sequence may be varied to produce beneficial products. However, if the alkyl phenol and formaldehyde are first reacted, a better reaction is effected by employing acid alkyl phenol containing some sulfuric acid alkylation catalyst, since the formaldehyde condensation reaction is facilitated by the presence of an acid or alkaline catalyst. If ordinary alkyl phenol is employed, the ammonium hydroxide will catalyze the formaldehyde condensation as long as it is present when the formaldehyde is introduced.

The mono-alkyl phenols used in preparing both (1) the metallo compound and (2) the ammonia condensation product have from 4 to 12 carbon atoms in the alkyl substituent. Thus, the alkyl substituent includes normal or branched chain butyl, amyl, hexyl, heptyl, octyl, decyl and dodecyl radicals. A preferred alkyl substituent is the .tetramethylbutyl radical. The mono-alkyl phenols are preferably obtained by alkylating in known manner, in the presence of concentrated sulfuric acid, phenol with olefins having from 4 to 12 carbon atoms. Olefins, such as butenal, isobutylene, the amylenes, di-isobutylene and tri-isobutylene are conveniently employed. It is preferred to conduct the alkylation with di-isobutylene since the resulting product is primarily para tetramethylbutyl phenol.

In view of the multiple points of the respective molecules at which the reactants may react, it is believed that a mixture of compounds is obtained in preparing both types of compounds. The designation of reaction product (1) as a metallo compound and of product (2) as a condensation product is intended to cover all the compounds present therein.

The following example illustrates a preparation of product (1), a typical metallo compound used in our fuel oil compositions in combination with product (2) EXAMPLEI Into a jacketed iron reaction vessel (No. l) were charged 12.9 parts by weight of phenol and 16.5 parts by Weight of di-isobutylene. The vessel was closed and the mixture agitated. Then 0.6 part by weight of 9498 per cent sulfuric acid was added. Cold water was run through the jacket of the reaction vessel in order to maintain a reaction temperature below 220 F. When all of the materials had been added, the temperature was permitted to attain 220 1?. and held at that temperature for four hours. The resulting para tetramethylbutyl phenol was dissolved in 73 parts by weight of a mineral lubricating oil.

Into an enamel lined reaction vessel (No. 2) were charged 4.6 parts by weight of calcium hydroxide with sufiicient Water to make a slurry to which was added 14.9 parts by weight of a 37 per cent by weight aqueous solution of formaldehyde. The reactants were heated to a temperature of 160 F. for two hours. Thereafter, the reaction product of the calcium hydroxide and formaldehyde was added to the mineral oil solution of para tetramethylbutyl phenol in reactor vessel No. 1 with agitation for 15 minutes. Then 4.3 parts by weight of aniline were added and the temperature maintained below 200 F. The condensation product was then dried by increasing the temperature to 280 F., distilling oil the Water, following which the productwas filtered. The concentrate thus prepared had the following properties:

Gravity, API ;e 20.3 Viscosity, SUV, 210 F 111.4 Color, NPA e 4.75 Neutralization No 0.92 alk. Ash as sulfate, per cent 4.513

The reactants in the above example were in the molar proportions of about 1.0 mol of calcium hydroxide, 3.0 mols of formaldehyde, 2.3 mols of para tetramethylbutyl phenol and 0.7 mol of aniline.

The following example illustrates a preparation of product (2), a typical condensation product used in our fuel oil compositions in combination with product 1) I EXAMPLEII Two hundred and ten parts by weight of octyl phenol were melted at 140 F. During agitation at this temperature, 57 parts by weight of ammonium hydroxide containing 29.8 per cent ammonia, and 122 parts by weight of a 37 per cent aqueous solution of formaldehyde were slowly added. The mixture was heated at 170 F. and agitated while maintaining that temperature for a period of 5 hours. Thereafter, the reaction product was dried at 290 F., distilling off the water added during the course of the reaction, and produced by the reaction. The product was then blended with a sufficient quantity of 70/2 Texas oil to product a 50 per cent concentrate (2700 grams oil to every 2540 grams octyl phenol used). The concentrate thus prepared had the following properties:

Gravity, API 15.8 Viscosity, SUV, 210 F 119.0 Color, NPA 2.5 Neutralization No 0.06 pH value 9.3

Color Amber Specific gravity, 77 F./77 F 1.9.379 Melting point, F 98-110 Solubility in No.2 fuel oil, per cent 5.0+

The following example illustrates a typical mixture of the products used in our fuel oil compositions.

EXAMPLE III A blend was prepared employing 50 per cent by weight of the product prepared in accordance with Example I and 50 per cent by weight of the product prepared in accordance with Example II in a mineral oil solvent. The concentrate thus prepared had the following properties:

Gravity, API 18.7 Viscosity, SUV, 210 F 1298 Color, NPA 4.75 dil Neutralization No 0.44

We have found that mixtures of the above-described reaction products, such as the blend of Example III and other mixtures wherein the weight ratio of each product with respect to the other ranges from about 1:4 to 4:1, may be coinpounded with a wide variety of hydrocarbon fuel oils to impart more advantageous properties thereto than would be expected from the separate actions of the two products. For example, both cracked and uncracked distillates and mixtures thereof in the fuel oil boiling range, that is, hydrocarbons boiling within the range of about 350 to 750 F., are stabilized against oxidative de terioration and the formation of undesirable contaminants by a minor amount of the mixed products set forth. By way of illustration, some of the most commonly used fuel oils which are benefitted by the mixed products are numbers 1, 2 and 4 fuel oils, the requirements'for which are specified in A. S. T. M. specification D 39648 T. These specifications appear hereinafter under Table I.

Table I Grade of Fuel Oil N0. l-A distillate No. 2-A distillate oil intended for oilfor gcneralpur- No. 4-1111 oil for vaporizing potpose domestic burner Installatype burners and heating for use tion not equipped other burners re- 1n burners not rewith preheating quiring this grade quiring No. 1 Fuel facilities of fuel Oil Flash Point, F min. 100 or legal... min. 100 or legal"..- min. 130 or legal. Pour Point, F max. 0...... max. 20 max. 20.

Carbon Residue on 10% Bottoms, Percen Distillation, F.:

10% at, F F

at, End Point, F.

Viscosity, SUV, seconds, F Viscosity, Kinematic, Centis'toks', 100 F Copper Strip Test, 122 F., 3 Hr Corrosion Test, 122 F., 3 Hr Viscosity, SUV, seconds, 100 F As further illustrative of fuels which are benefitted by the mixed products, the specifications for certain diesel fuel oils as prescribed by A. S. T. M. Designation: D 975-48 T are set forth in Table II.

Table II 8 The colorwas also-noted. This test bears the designation Gulf Method 327, Modified.

Another test was devised to simulate, on an accelerated basis, the conditions and effects pre- Grade of Fuel Oil No. l-D-A volatile distillate fuel oil for engines in service requiring frequent speed and load changes No. 2-DA distillate fuel oil of low volatility for engines in industrial and heavy mobile service N o. 4-D-A fuel oil for low and medium speed engines Flash Point, F i. Pour Point, Water and Sediment, Percent by Vol Carbon Residue on 10% Bottoms, Percent Ash, Percent by Wt Distillation:

7 at F En d Pbint, F

min. 100 or legal.-.

Sulfur, Percent by Wt. Copper Strip Corrosion Octane Number min. 100 or legal-.- min. 130 or legal.

max. 20. max. 0.50.

max. 0.10.

In accordance with our invention, small proportions of the herein-described mixed products in fuel oils will substantially reduce the tendency to form insoluble constituents, undesirable color bodies and the tendency of the fuel to clog 4 screens and filters in burners and other equipment. The amount of mixed products used is suflicient to stabilize the fuel oil against the formation of sludge or insoluble bodies, and in general, small amounts, from 0.001 to 5.0 per cent by weight on the fuel oils, will sufiice. The additives, either separately or in combination, may be dispersed in fuel oil stocks directly by simple mixing, or they may be introduced to the fuel oil in the form of a concentrate of the additive in a minor amount of a fuel oil or hydrocarbon solvent which may be more readily blended with fuel oil.

To determine the effectiveness of the said mixed product on inhibiting the formation of sludge and stabilizing the color of the oil, tests were conducted on No. 2 furnace oils both before and after treatment with the mixed products of Example III. Of these tests, an oxidation test was selected as most indicative of the environment which appears to induce the formation of sludge and undesirable color bodies. For this purpose A. S. T. M. oxidation test D 943-47 T was modified somewhat by eliminating the iron and copper catalyst coils as prescribed by the test. In other words, the A. S. T. M, test procedure as outlined in test D 943-47 T was followed employing the glass parts of the A. S. T. M. oxidation assembly for blowing a sample of the fuel oil with oxygen. Briefly, the test employed comprised placing a 300 cc. sample of the fuel oil in a flask immersed in an oil bath at 300 F. and blowing oxygen through the sample for a period of two hours at the rate of 3 liters of oxygen per hour. The sample was then filtered and the weight of insoluble material or sludge formed was noted.

vailing upon long exposure of fuel oil to copper screens in burner systems. In brief the test com prises exposing a sample of fuel oil in the presence of a copper screen to ultraviolet light and observing the effects after the lapse of a specific period of time. The oil was placed in standard quartz tubes holding cc. samples, the quartz tubes providing full effect for the ultraviolet light without the error that may occur with glass tubes which absorb actinic light rays, A 2 by 3 in., 60 mesh, copper screen, bent in the form of a cylinder, was suspended in the middle of the oil in each quartz tube by means of two fine wire hangers placed through two side slots of the top cork. The tubes were then placed in a Weatherometer at a distance of about 10 inches from a source of ultraviolet light derived from a standard type C3 B Eveready carbon arc solarium unit. The temperature was maintained at 111 F., and the exposure continued for a period of 24 hours, after which the color and general appearance of the oil were noted. This test bears the designation Gulf Method 332, Modified."

EXAMPLE IV A series of tests were conducted on a number of fuel oils both before and after the addition of varying proportions of the mixed products prepared in accordance with Example III to determine the eifectivenes of the mixed products for stabilization of fuel oil. This fuel oil was comprised essentially of a mixture of straight run and catalytically cracked distillates obtained from Venezuela, Kuwait and Mara, and Louisiana crudes. The results of the oxidation and ultraviolet light stability tests described above appear hereinafter in Table III. All the inspection tests were not repeated for each run since the additive, in the amounts employed, has a negligibl effect on gravity, viscosity, color, neutralization number and the like.

Table III Inhibited Fuel Oils Make-up No. 2 Fuel Oil, Percent by Wt.:

Uncracked distillates Cat. cracked distillates. Additive, 50% Product (1) and 50% Prodnot (2), Lb./1,000 bbl.

Inspection:

Gravity, API Viscosity, SUV, 100 F Color, NPA Neutralization No Carbon Residue on 10% Bottoms, Percent. Oxidation Test-Method 327, Gulf, Mod.

300 F. 3 l. Oxygen/En, 2 H12, 300 00.: Color, NPA, Unfiltered. Color, NPA, Filtercd Insoluble, Mg./300 cc Ultraviolet Light Stability-Method 332,

Gulf, Mod-Quartz tube, 111 F., 24 Hrs. 6 sq. in. Copper Screen:

75. 75 (0.025% by Wu).

Color, NPA 5.5... 5.0 5.0 5.0. Appearance hvy.ppt mod. ppt mod. ppt bright.

It is readily seen from the data in Table III Table V that very small proportions of the inhibitor prepared in accordance with Example III are suificient to stabilize fuel oils against the formation Inhibited of sludge and undesirable color bodies. o l Fuel OHS XAMP Make-upNo.2Fuel Oil, Perceutb Wt: E m v Uncracked distillates "K..."

The same tests were conducted on a fuel oil of somewhat diiferent composition, the proportion of uncracked to cracked distillates being much higher than that of the fuel oil employed in Example IV. The results of these tests, also supporting the efiectiveness of the mixed products of Example III, appear in Table IV.

Table IV Uninhibited Inhibited No. 2 Fuel No. 2 Fuel Oil Oil Make-up No. 2 Fuel Oil, Percent by Wt.:

Uncracked distillate 93. Cat. cracked distillates 7. Additive, 50% Product (1) and 50% 30 (0.01% Product (2), LIL/1,000 Bbl. by Wt). Inspection:

Gravity, API Color, NPA Carbon Residue on 10% Bottoms, Oxidation Test-Method 327, Gulf, Mod.300 F. 3 1. Oxygen/Hm, 2 Hrs, 300 cc.: 7 Color, NPA, Unfiltered 2.5. Color, NPA, Filtered. 2.5. Insoluble, lug/300cc. 4. Ultraviolet Light Stab1lity. lo ,hod 332, Gulf, Mod.Quartz tube, 111 F. 24 Him, 6 sq. in. Copper Screen:

Color, NPA I. 4.0 4.0. Appearance mod. ppt. v. 11:. ppt.

EXAMPLE VI Another fuel oil bearing the same ratio of uncracked to cracked distillates, as the oil tested in Example V, was subjected to the same oxidation and ultraviolet light stability tests both before and after the addition of 0.03 per cent by weight of the product of Example III. In addition, a simple aging test was also employed wherein samples of the oil were placed in a window exposed to sunlight at room temperature for a period of ten days, after which the color and general appearance of the oil were noted. The results of these tests appear hereinafter in Table V.

Cat. cracked distillates Additive 50% Product (1) and 50% Product (2), Lb./l,000 bbl. Inspection:

Gravity, API Color, NPA.. Neutralization No Carbon Residue, Percent U-V Light Stability-Method 332, Gulf Mod.Quartz Tube, 111 F., 24 Hr., 6 sq. in. Copper Screen:

Color, NPA 8.0 2.0. Appen-rance ppt bright Aging Test, Room Temp, Window,

10 days:

Color, NPA 7.0 2.0, Appearance cloudy bright Oxidation Test-Method 327, Gulf, Mod.300 F., 3 l. Oxygen/En, 2 Hr., 300 cc. Oil:

Color, NPA 7.5 2.5. Color, NPA, Filtered 2.25. Insoluble, Mg./300 cc 70 2.

EMM'PLE VII To determine the effectiveness of the combination of product (1) and product (2) in fuel oils, in relation to the separate action of each product respectively, the above described oxidaticn test was conducted on No. 2 fuel oil samples comprised of per cent uncracked and 25 per cent cracked clistillates, and separately containing varying proportions of product (1) and product (2); also tested were samples containing varying proportions of the combined products prepared in accordance with Example III, that is, 50 per cent by weight of product (1) and 50 per cent by weight of product (2) A comparison of the test results, in terms of milligrams of insolubl material per 300 cc. of fuel oil after oxida tion for 2 hours, appears hereinafter in Table VI.

Table VI clearly establishes that the combina- 11 tion of both products produces a greater degree of stabilization of fuel oil than would be expected from the separate action of each product. Why this occurs is not understood, but the fact remains that a coaction exists when product (1) and product (2) are incorporated in fuel oils, to impart extraordinary stabilization. The use of product (1) in combination with product (2) also takes advantages of the improved detergency of the metallo compound of product (1) while still utilizing the beneficial effects of product (2), since the metal present in product (1) appears to furnish a detergent action which facilitates maintaining burner screens and burners free from deposits and sludge.

It is apparent from the above examples that mixtures of the products described hereinabove remarkably inhibit the formation of sludge in furnace oils, and further, substantially stabilize the color thereof. Thus, very small amounts of the inhibitors set forth are sufficient for retarding the development of color and sediment in fuel oils upon aging.

Under certain conditions, however, the rusting of iron surfaces of storage tanks or other equipment may be encountered, particularly where promoted by the presence of water. For

'most purposes the improved fuel oils of our invention are stabilized against the formation of rust, but where extreme conditions are encountered which unduly aggravate rust and corrosion, it is contemplated within the scope of our invention to include in the fuel oils other inhibitors to retard the formation of rust and prevent corrosion. Such rust and corrosion inhibitors are well known in the art and a wide variety of them can be employed where necessary.

Resort may be had to such modifications and variations as fall within the spirit of the invention and the scope of the appended claims.

What we claim is:

1. A fuel oil composition comprising a major amount of a hydrocarbon fuel oil and a minor amount, sufficient to stabilize the fuel oil against the formation of sludge, of (1) the reaction product prepared by reacting an aqueous slurry of 1 mol of a metal hydroxide selected from the group consisting of barium, strontium, magnesium and calcium hydroxides with from 2 to 4 mols of formaldehyde at a temperature not exceeding 200 F. and condensing the resulting product with from 0.5 to 1 mol of aniline and from 2 to 4 mols of a mono-alkyl phenol having from 4 to 12 carbon atoms in the alkyl substituent, and (2) the reaction product prepared by reacting, at a temperature not exceeding 200 F., 1 mol of ammonium hydroxide with from 1 to mols of formaldehyde and from 1 to 4 mols of a monoalkyl phenol having from 4 to 12 carbon atoms in the alkyl substituent, the weight ratio of product (l) to product (2) ranging from about 1:4 to 4:1.

2. The composition of claim 1 wherein the mixture of said reaction products is present in an amount of from 0.001 to 5.0 per cent by weight of the fuel oil.

3. A fuel oil composition comprising a major amount of a hydrocarbon fuel oil and a minor amount, suflicient to stabilize .the fuel oil against the formation of sludge, of substantially equal quantities of (1) the reaction product prepared by reacting an aqueous slurry of 1 mol of a metal hydroxide selected from the group consisting of barium, strontium, magnesium and calcium hydroxides with from 2 to 4 mols of formaldehyde at a temperature not exceeding 200 F. and condensing the resulting product at a temperature not exceeding 200 F. with from 0.5 to 1 mol of aniline and from 2 to 4 mols of a mono-allzyl phenol having from 4 to 12 carbon atoms in the alkyl' substituent, and (2) the reaction product prepared by reacting, at a temperature not exceeding 200 F., 1 mol of ammonium hydroxide with from 1 to 5 mols of formaldehyde and from 1 to 4 mols of a mono-alkyl phenol having from 4 to 12 carbon atoms in the alkyl substituent.

4. A fuel oil composition comprising a major amount of a hydrocarbon fuel oil and a minor amount, sufiicient to stabilize the fuel oil against the formation of sludge, of substantially equal quantities of (l) the reaction product prepared by reacting an aqueous slurry of about 1 mol of calcium hydroxide with about 3 mols of formaldehyde at a temperature of about F., and condensing the resulting product with about 0.7 mol of aniline and 2.3 mols of para tetramethylbutyl phenol at a temperature not exceeding 200 F., and (2) the reaction product prepared by reacting, at a temperature not exceeding 200 F., about 1 mol of ammonium hydroxide with about 1.5 mols of formaldehyde and 1 mol of para tetramethylbutyl phenol.

HERSCHEL G. SMITH.

TROY L. CANTRELL.

JOHN G. PETERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,348,638 Mikeska et a1. May 9, 1944 2,431,011 Zimmer et a1. Nov. 18, 1947 

1. A FUEL OIL COMPOSITION COMPRISING A MAJOR AMOUNT OF A HYDROCARBON FUEL OIL AND A MINOR AMOUNT, SUFFICIENT TO STABILIZE THE FUEL OIL AGAINST THE FORMATION OF SLUDGE, OF (1) THE REACTION PRODUCT PREPARED BY REACTING AN AQUEOUS SLURRY OF 1 MOL OF A METAL HYDROXIDE SELECTED FROM THE GROUP CONSISTING OF BARIUM, STRONTIUM, MAGNESIUM AND CALCIUM HYDROXIDES WITH FROM 2 TO 4 MOLS OF FORMALDEHYDE AT A TEMPERATURE NOT EXCEEDING 200* F. AND CONDENSING THE RESULTING PRODUCT WITH FROM 0.5 TO 1 MOL OF ANILINE AND FROM 2 TO 4 MOLS OF A MONO-ALKYL PHENOL HAVING FROM 4 TO 12 CARBON ATOMS IN THE ALKYL SUBSTITUENT, AND (2) THE REACTION PRODUCT PREPARED BY REACTING, AT A TEMPERATURE NOT EXCEEDING 200* F., 1 MOL OF AMMONIUM HYDROXIDE WITH FROM 1 TO 5 MOLS OF FORMALDEHYDE AND FROM 1 TO 4 MOLS OF A MONOALKYL PHENOL HAVING FROM 4 TO 12 CARBON ATOMS IN THE ALKYL SUBSTITUENT, THE WEIGHT RATIO OF PRODUCT (1) TO PRODUCT (2) RANGING FROM ABOUT 1:4 TO 4:1. 